The overall objectives of this project are: to study the antigenic and immunobiologic properties of normal and leukemic leukocytes which have been tagged with dinitrofluorobenzene; to determine whether antisera prepared against DNP-tagged cells can be employed for the serodiagnosis of leukemia; to develop immunotherapy models of leukemia and lymphoma using DNP-tagged cells as the immunizing antigen. During the year 1975-1976 we have: l) Further defined the effects of dinitrophenylation on the cell surface membrane by using lectins as molecular probes. Untagged and DNP-tagged granulocytes bound equivalent amounts of Con A although tagged cells were preferentially agglutinated. DNP tagged lymphocytes showed a significant reduction in their responsiveness to phytomitogens (PHA, Con A and Pokeweed Mitogen) which could be attributed to an alteration in triggering; 2) Studied the effects of dinitrophenylation on the expression of HLA antigens. A variable pattern of reactivity was observed with lymphocytotoxic sera following treatment of peripheral blood lymphocytes with 10 to the 4th power molecules of DNFB per cell while in contrast cells were uniformly less reactive or non-agglutinable with HLA leukoagglutinating antisera; 3) Developed immunotherapy models employing DNP-tagged cells as the immunogen. DBA/2 mice were given DNP-tagged L1210 cells and subsequently challenged with L1210 either alone or in combination with C. parvum. A significant prolongation in survival time was noted in animals receiving DNP-tagged cells together with C. parvum compared to those which had received either tagged cells or C. parvum alone; 4) Further defined the serologic reactivity which had been prepared against DNP-tagged leukocytes. Membrane extracts prepared from DNP-tagged cells appeared to be capable of evoking the production of cytotoxic antibodies which had residual reactivity against leukemic cells from patients with acute and chronic lymphocytic leukemia and acute myelogenous leukemia. BIBLIOGRAPHIC REFERENCES: Barth, R.F., Singla, O., Studies on the hematogenous dissemination of technetium-99m labeled malignant cells. In Role of Macrophages in Neoplasia. Academic Press, 1976.